344 Mr Gorry, On some points in the structure and [April 30, 



object upon it can be read while the telescopes are fixed. It can 

 be used as a repeating circle if desired. There are adjustments 

 for level of the telescopes and they can each be rotated in azimuth 

 on their brackets when it is required to use them with a combi- 

 nation of prisms. 



The instrument is provided with a prism with three polished 

 faces giving refracting angles of 45°, 60° or 75° at pleasure and 

 good definition in each position. The same prism can be used 

 as a "half-prism" by placing its short face nearly perpendicular 

 to the axis of the collimator, when the light will undergo in- 

 ternal reflexion at the next face and be dispersed at emergence 

 from the third face. In this position of the prism the telescope 

 and collimator are parallel and nearly in the same straight line, so 

 that the instrument can be used as a direct vision spectroscope 

 which is sometimes useful. 



The instrument has been well constructed by A. Hilger of 

 Stanhope Street, London, N.W., and is shewn in the photograph, 

 Plate ix. 



(4) On some points in the structure and development of the Leaves 

 of Pinus Silvestris L. By T. H. Corry, B.A., Caius College. 



Beyond a few scattered notices 1 and figures of the adult leaf, 

 fairly accurate but by no means satisfactory, the minute structure 

 and development of the leaves of Pinus, though they present many 

 features of peculiar interest, seem to have been hitherto passed over 

 without almost any notice by investigators. F. Hildebrand it is 

 true has contributed to the Botanische Zeitung 2 the results of a 

 somewhat cursory comparative study of the appearances presented 

 by the adult stomata in various members of the Coniferae, while 

 Sachs has expressed his idea as to the method of origin of the so- 

 called " intrusive ingrowths" in the cells of the cortical pallisade 

 ground-tissue of Pinus. E. Strasburger 3 has studied completely the 

 development of the stomata in Salisburia, Dammara, and Araucaria. 

 Haberlandt also has endeavoured to explain the physiological func- 

 tion which the "intrusive ingrowths" exercise and the need for 

 their occurrence. Further than this no account has been given. 



I have been engaged at intervals for some time past in studying 

 the features which these leaves present, but since a considerable 

 time must necessarily elapse during the preparation of a series of 



1 C. E. Bertrand, " Anatornie Comparee des Tiges et des Feuilles chez les Gneta- 

 cea; et les Coniferae," Ann. des Set. Nat., Ser.v. Vol. xx. 1874, pp. 5—153, PI. 1 — 12. 



2 "Der Bau der Coniferenspaltoffnungen und einige Bemerkungen iiber die 

 Vertheilmig derselben." Bot. Zeit, I860, No. 17, pp. 149—152, PI. iv. 



3 E. Strasburger, "Zur Entwicklungsgeschichte der Spaltoffnungen." rrings- 

 heim's Jahrbucher fur Wissenschaftliche Botanik, Vol. v. Pt. 3, 1867, pp. 297—342, 



Pis. XLT. XLII. 



